An Evidence-Based Medicine Approach To Plantar Fasciitis

Taking an exhaustive look at the literature on plantar fasciitis, this author discusses what studies have revealed on diagnostic imaging and explores the reported findings for a wide range of treatments, including orthotics, platelet rich plasma, extracorporeal shockwave therapy and plantar fasciotomy.

Plantar fasciitis remains one of the most common pathologic conditions for which patients seek podiatric care. Tong and Furia estimated that the cost to treat plantar fasciitis in Medicare patients alone may be as high as $376 million a year.1

There is an evolving standard of care for the treatment of plantar fasciitis. With this in mind, let’s take a closer look at changing concepts in etiologic considerations, the diagnosis of plantar fasciitis, conservative management and surgical treatment.

Clinicians have long recognized overweight status as an etiologic factor in plantar fasciitis. Sadat noted a mean body mass index (BMI) of 30.36 in symptomatic patients in comparison to non-symptomatic patients with a mean BMI of 26.71.2 Similarly, Rano and colleagues relate an average BMI of 30.4 in heel pain patients in comparison to 28.2 in asymptomatic patients.3 These authors also noted no relationship between foot type and plantar fasciitis, but did observe that plantar fasciitis occurs more often in less active individuals. Riddle and colleagues noted that BMI was a major factor responsible for disability and functional impairment with heel pain.4 Given that heel pain is associated with increased BMI in many patients, a recommendation for weight loss is appropriate in this patient population.

There have been some advocates for changing terminology from plantar fasciitis to plantar fasciosis. This is based upon the work of Lemont and coworkers, who studied 50 histologic specimens from plantar fasciitis patients and found no evidence of an inflammatory process.5 The authors instead found myxoid degeneration, fragmentation of plantar fascia, degeneration of the plantar fascia and bone marrow vascular ectasia.

However, the presence of ultrasound demonstrable changes, such as resolved hypoechogenicity and decreased plantar fascia thickness, following the treatment of plantar fasciitis suggest the presence of a more active and dynamic process.6 Utilizing ultrasound, Fabrikant and Park demonstrated decreased plantar fascia thickness in response to injection and biomechanical therapy, again implying a more dynamic pathologic process.7 More recently, Mahowald and coworkers showed that changing thickness of the plantar fascia is a valid objective measurement to assess treatment protocols.8

Hafner and colleagues have also suggested a diverse etiology for plantar fasciitis in a study looking at 100 pathologic specimens in patients with recalcitrant plantar fasciitis.9 The authors found that 25 percent of patients demonstrated neoplastic changes consistent with plantar fibromatosis, 21 percent had inflammatory changes and 54 percent showed no inflammatory or neoplastic changes. Given these findings, the authors suggested that the etiology of plantar heel pain may be more diverse than frequently assumed and a more detailed evaluation may be appropriate in some patients.

A Closer Look At Biomechanical Considerations

Other authors have suggested that reduced foot mobility and decreased shock absorption may cause plantar heel pain as they demonstrated through assessment of nonweightbearing and weightbearing lateral radiographs of the foot, and measurements of calcaneal inclination, first metatarsal-calcaneal inclination and plantar fascia length.10 Researchers have also pointed to the decreased ability of the plantar fat pad to dissipate contact phase energy as being associated with plantar heel pain.11

Although both excessive pronation and supination are suggested causes of plantar heel pain, Riberio and coworkers demonstrated that there was no difference in hindfoot alignment in runners with or without plantar fasciitis although runners with plantar fasciitis tended to have higher arches.12 Studies have demonstrated decreased ankle joint dorsiflexion to be present in many patients with plantar fasciitis.13,14 This reinforces the role of dorsiflexion exercises, night splints or gastrocnemius recession in the treatment of plantar fasciitis. Multiple studies have demonstrated the successful use of night splints for the treatment of plantar fasciitis and reduction of ankle equinus.15,16 Similarly, stretching of the gastrocnemius and the plantar fascia can reduce pain and activity restriction.17,18

Key Diagnostic Insights

In addition to ensuring a thorough patient history and clinical examination, one may utilize a variety of diagnostic imaging techniques for the evaluation of plantar fasciitis. These include radiographs, ultrasound, magnetic resonance imaging (MRI), scintigraphy and elastography.

In several studies, researchers have found that increased plantar fascia thickening with diffuse hypoechogenicity is associated with symptomatic plantar fasciitis, particularly when the plantar fascia is greater than 4.0 mm.19,20 Studies of intra-observer reliability utilizing ultrasound for the diagnosis of plantar fasciitis, even by experienced sonographers, have suggested that reliability increases when clinicians use an average of three separate measurements rather than one.21 Researchers have also noted that changes in thickness greater than 0.6 mm represent true thickening of the plantar fascia.21

Clinicians may also use magnetic resonance imaging to evaluate recalcitrant heel pain. One study characterized atypical heel pain as being associated with bone marrow edema of the calcaneus and MRI confirmed the diagnosis of plantar fasciitis in 76 percent of patients.22 Another study demonstrated the presence of bone marrow edema and fascial tears utilizing MRI although the authors noted no difference in clinical response from patients with plantar fasciitis.23

Scintigraphy can help predict patient response to the treatment of plantar fasciitis. Noting three patterns of uptake in plantar fasciitis, Frater and colleagues found that treatment response was most predictable with focal uptake versus diffuse uptake along the plantar fascia or uptake along the proximal plantar fascia.24 This indicates a less typical presentation of plantar fasciitis and a decreased response to treatment.

The measurement of plantar fascia elasticity utilizing elastography is reportedly 95 percent sensitive/100 percent specific for the diagnosis of plantar fasciitis in comparison to ultrasound with a 65.8 percent sensitivity and 75 percent specificity.25

A Guide To The Non-Operative Management Of Plantar Fasciitis

It has long been established and generally accepted that plantar fasciitis responds well to non-operative management. Utilizing anti-inflammatory medication, heel cushions, stretching, relative rest and injection therapy, Davis and coworkers demonstrated an 89.5 percent resolution of heel pain over 10.9 months.26

Although clinicians frequently utilize therapeutic ultrasound in the treatment of plantar fasciitis, it is somewhat controversial. Researchers have found that ultrasound is associated with a 30 percent reduction in treated patients versus a 25 percent reduction in sham ultrasound patients.27 In another study, stretching plus sham ultrasound yielded better results (54.6 percent improvement) than did stretching plus ultrasound (46.5 percent improvement).28

While clinicians commonly employ iontophoresis for the treatment of plantar fasciitis, one study found no difference at one month between placebo and iontophoresis utilizing 0.4% dexamethasone.29 Another study demonstrated strapping of the foot to be superior to iontophoresis.30

Studies supporting the utilization of orthotics for the treatment of plantar fasciitis are not overly convincing. Pfeffer and colleagues demonstrated the superiority of stretching exercises only, rubber inserts, felt inserts and silicone inserts in comparison to custom orthotics for the treatment of plantar fasciitis.31 Landorf and coworkers demonstrated that a prefabricated orthotic was superior to customized orthotics for the reduction of plantar fascia pain.32 Turlik and coworkers, however, demonstrated that orthotics were superior in the treatment of plantar fasciitis versus heel pads although both groups demonstrated a reduced duration and severity of heel pain.33

Landorf and colleagues noted that while orthotics play a role in the treatment of plantar fasciitis, no randomized, controlled trials or other good evidence existed to recommend orthotics over prefabricated supports.34 The authors recommended the initial use of prefabricated supports prior to the initiation of formalized orthotic management.

Studies have demonstrated the utilization of rocker soles with orthotics to be superior to the use of orthotics alone, or the use of orthotics without rocker shoes.35,36

In the treatment of recalcitrant plantar fasciitis, authors have demonstrated below-the-knee casts to be associated with a 25 percent complete resolution of pain and improvement in pain in 61 percent of patients.37

How Effective Is Injection Therapy For Plantar Fasciitis?

Authors have advocated a variety of injection therapies for the treatment of plantar fasciitis.38 These include dry needle techniques, the injection of local anesthesia, corticosteroids and autologous substances such as platelet-rich plasma (PRP) or other blood-derived products, sclerosants, mesenchymal and stem cell injection as well as prolotherapy with hyperosmolar dextrose.

Physicians have frequently used corticosteroid injection to treat plantar fasciitis. One study documented rupture of the plantar fascia after an average of 2.67 injections in 2.4 percent of patients in one study while Acevedo and coworkers reported 44 plantar fascial ruptures in 765 patients receiving corticosteroid injections and Sellman reported 37 plantar fascial ruptures following corticosteroid injection.39-41

Research has demonstrated corticosteroid injection for the treatment of plantar fasciitis as more cost effective and superior to extracorporeal shockwave therapy at three months and 12 months.42 Although advocated by many who cite greater accuracy of injection placement, studies have demonstrated no difference in response to ultrasound guided injection for plantar fasciitis versus palpation guided injection of corticosteroid injection for plantar fasciitis.43 Research has not demonstrated the use of a posterior tibial nerve block in conjunction with plantar fascia injection therapy, including ultrasound guided posterior tibial nerve block, to offer any clinical advantage.44,45

Recently, authors have advocated PRP and autologous growth factors for the treatment of plantar fasciitis. Kiter and colleagues demonstrated a superior outcome when injecting autologous growth factors with 2% prilocaine versus prilocaine injection alone or the use of methylprednisolone acetate alone.46 The authors did note that all three techniques resulted in reduction of pre-treatment pain. Multiple studies have shown the injection of PRP for the treatment of plantar fasciitis is effective.47-50 A comparison of methylprednisolone/local anesthesia injection versus PRP/local anesthesia injections demonstrated superior outcome with the use of PRP although both techniques resulted in substantial diminution in pain reduction with no difference in Roles and Maudsley scores.51 However, others have demonstrated superior clinical results with the use of corticosteroid injection versus autologous growth factor injection although researchers found that both were efficacious.52

OnabotulinumtoxinA (Botox, Allergan) injections have been particularly effective for the treatment of plantar fasciitis.53 Multiple studies have reported significant improvement in the treatment of plantar fasciitis utilizing Botox injections with or without the addition of local anesthesia, or the addition of autologous growth factors.54-57 In a study comparing botulinum toxin A versus corticosteroids for the treatment of plantar fasciitis, both groups improved although there was a slightly better outcome with the use of botulinum toxin A.58

What The Research Says About Surgery For Plantar Fasciitis

One common surgical approach for the treatment of plantar fasciitis is microdebridement via the Topaz device (ArthroCare). A recent study demonstrated the initial superiority of open Topaz technique versus a percutaneous technique at one year.59 Multiple studies have suggested that the use of radiofrequency Coblation is associated with success rates equivalent to open plantar fasciotomy and a faster return to normal activity with reduced complications and reduced pain in comparison to plantar fasciotomy.60-64

Several studies have documented successful outcomes with radiofrequency nerve ablation in the treatment of chronic plantar fascia pain.65,66 Similarly, cryosurgical nerve ablation is reportedly successful in the treatment of recalcitrant plantar heel pain.67

Various authors have advocated pronation limiting surgery, including gastrocnemius recession, subtalar joint arthroereisis and calcaneal osteotomy, for the treatment of recalcitrant plantar fasciitis.68-71

Assessing The Outcomes With Plantar Fasciotomy

One may perform plantar fasciotomy through a variety of techniques including a percutaneous approach, an in-step plantar fasciotomy, a single or dual-port endoscopic plantar fasciotomy or the DuVries type of open plantar fasciotomy. Traditional open surgical techniques have long been associated with good outcomes and one study reported 71 percent good or excellent results.72

The in-step plantar fasciotomy has resulted in complete relief in 2.6 percent of patients while 97.8 percent of patients related an 80 percent resolution of pain.73 Other studies have reported percutaneous plantar fasciotomy to have 83 percent good to excellent outcomes.74,75 Endoscopic plantar fasciotomy utilizing a single or dual-port technique is associated with supportive studies generally demonstrating good outcome for the treatment of plantar fasciitis.76-79

A Look At Other Techniques For Heel Pain

Brook and coworkers reported on the successful use of radiofrequency electromagnetic field therapy for the treatment of plantar fasciitis.80 Gordon and colleagues reported recent success with the use of extracorporeal pulse activated therapy.81 Both of these techniques offered the advantage of noninvasive management of plantar fasciitis.

Authors have described radiation therapy as successful for the treatment of plantar fasciitis in multiple recent publications and one may consider this as an additional noninvasive therapeutic alternative for the treatment of plantar fasciitis.82

For some time now, experts have advocated extracorporeal shockwave therapy (ESWT), both low- and high-energy, with and without ultrasound guidance. Generally, reported results for the use of ESWT have been favorable but they do vary. Speed and colleagues reported that at three months, only 37 percent of active ESWT patients improved while 24 percent of sham patients had improved.83 In a randomized double-blind placebo controlled study, Buchbinder and colleagues demonstrated no difference between shockwave and a placebo in the treatment of plantar fasciitis.84

Conversely, Ogden and coworkers demonstrated a 95 percent improvement at one year utilizing ESWT for the treatment of plantar fasciitis.85 A meta-analysis of shockwave for the treatment of plantar fasciitis revealed an overall success rate of 80 percent and recommended consideration of this technique prior to surgical intervention.86 Othman and coworkers found that endoscopic plantar fasciitis demonstrated a superior outcome in comparison to ESWT in the treatment of plantar fasciitis while Rompe and coworkers found that stretching exercises yielded superior results to the utilization of low energy radial shockwave therapy.87,88

In Summary

Chronic plantar heel pain encompasses a variety of potential diagnoses including fasciitis, fasciopathy, fasciosis, fibromatosis, nerve entrapments and bursitis among other diagnoses. Various authors have advocated an eclectic array of therapies for the management of plantar fasciitis. In the majority of studies, researchers noted improvement in both the active treatment group as well as the placebo group.

A variety of existing conservative therapeutic options are generally reported as being successful in the treatment of plantar fasciitis. It would appear that non-operative management is typically indicated for the majority of patients with symptomatic plantar fasciitis. Bear in mind that most studies in the treatment of plantar fasciitis are characterized by small sample sizes and a failure to conceal active from sham treatment groups is also common. Accordingly, it is difficult to draw definitive conclusions as to the best non-surgical or surgical options for the treatment of plantar fasciitis. Overall, it does appear that a number of options are successful for the treatment of plantar fasciitis.

One should consider weight loss when indicated and reduction of mid-ankle joint dorsiflexion when indicated. It does appear that the use of orthotics with rocker bottom shoes increases the efficacy of orthotics for the treatment of plantar fasciitis.

There is no indication that ultrasound guidance for the treatment of plantar fasciitis provides any additional benefit to justify the increased costs. Corticosteroid injection for the treatment of plantar fasciitis has relevant literature support. The utilization of onabotulinum toxin injections is also well supported in the literature for the treatment of plantar fasciitis. The indications for the use of PRP remain unclear. Finally, the literature supports a number of surgical interventions but there is no indication of the superiority of one technique over another.

Dr. Jacobs is in private practice in St. Louis. He is a Fellow of the American College of Foot and Ankle Surgeons, and the Academy of Physicians in Wound Healing.